If radar or sonar systems are individually used to provide a signal that represents the positions of obstacles near a vehicle, the output data may suffer from false positives of the presence of obstacles because of noise and clutter or misdetections because of the reflectivity and relative aspect of the obstacles with respect to the vehicle. If false positives of obstacles are present, the vehicle may expend additional computational resources in obstacle avoidance or may stop or slow down unnecessarily interfering with the efficient execution of a mission. Thus, there is a need to combine information from multiple sensors to improve the accuracy in the detection of the presence or absence of obstacles around a vehicle. Further, there is need to make the combined information available even when the absolute or global position of the vehicle is not known with certainty.